For scrubbing organic particles present in the smoke from meat smoking plants, one common practice is to convey the smoke through a column containing pervious filler material onto which a caustic solution is sprayed. A substantial part of the organic particles are removed by oxidation but sludge builds up rapidly within the filler material and on the walls of the column; and the caustic may corrode the apparatus.
Biological air purifying systems recently have been utilized as the second stage of a two-stage process for metabolizing organic particles in the gas which flows from a catalyzing chamber, in which odor-producing substances are chemically processed. Such systems rely in their biological second stage on nourishing and cultivating bacteria which produce enzymes capable of hydrolyzing organic particles in air. In such processes a bacterial garden is to be generated in an air-pervious matrix. The prior art teaches the cultivation of a thriving population of bacteria to perform these functions. Supplemental nutrients are provided in order to promote and maintain their balanced growth and reproduction. Organic material contained in air passing through such columns may be metabolized, but slowly and only as a secondary consequence of this biolobical activity of which the production of hydrolyzing enzymes is but a minor part. Thus, only a small proportion of the total metabolic activity of the column represents biodegradation of the particulate matter contained in the air.
The prior art teaches that the effective metabolizing of air-borne particles is achieved only so long as balanced growth is maintained under essentially optimal nutritional circumstances. Balanced growth is physiologically very delicate; the presence of noxious materials in the air or shifts in temperature, pH, or nutrient concentrations readily disrupts the critical balance, which may be impossible to re-establish.
Another problem is a build-up of sludge, resulting from the incomplete metabolism of organic matter derived principally from the supplemental nutrients. Such sludge tends to clog the air flow or to accumulate inconveniently. An inherent limitation in the prior art, as it bears on the rate at which particles can be removed from air, is that the organic macromolecular components of smoke and other such gases consisting of cellulose, proteins, etc., cannot be utilized by bacteria directly, but first must be degraded into their constituents: simple sugars, amino acids, etc. Even a large thriving population of bacteria can slowly produce only limited amounts of the enzymes necessary to effect such degradation. Accordingly it is applicant's conclusion that the rate limiting step in any such process must be the step of initial hydrolysis into metabolizable subunits.